Not quite a lump of coal, but I’m sure some may view it that way. Mini-mugs are shot-glass size, standing about 2-1/4″ tall, and they date to the same pre-Prohibition era. Mini-mugs are collectible in their own right and there are hundreds, if not thousands of variants to chase after, but mini-mugs advertising a whiskey brand or a distiller are exceptionally rare. Offhand, I can only think of one, and that advertises Bellwood Rye Whiskey from McCarthy & Co. of Haverhill, MA.
Mini-mugs don’t get much respect from purist glass collectors, but they do make for an interesting and colorful addition to the display case. The Bellwood mug is actually quite rare, showing up for sale about once every 4 or 5 years on average.
whatilove00 listed one for sale mid-December with an initial bid price of $49.99. Unfortunately it had a significant chunk missing from the rim and the auction closed a week later without a buyer. In good condition, this mug can sell for in the region of $125, so the asking price was not unreasonable.
If you’re interested, the mug relisted at the same asking price and the auction was still running as of writing, no bidders.